Which molecule is nonpolar?

[oleoleoleole]

I've run into a couple of these "which molecule is nonpolar/polar" questions. I understand the question, but honestly, I have to do lewis structures to get the answer right. I don't want to waste 5 mins on a discrete. I've tried visualizing the molecules, but that only works with easy molecules like CO2 and CH4. Just by looking at the molecule, how am I supposed to know if it has a lone pair? Anyone have any suggestions?

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[loveoforganic]

You should be able to rule out a bunch of the choices just be general knowledge and quickly being able to see that it's nonpolar, e.g. The two examples you gave

 

[VicodinMan]

General knowledge and look for functional groups and weird stuff whenever you draw a ball n' stick model.